Genetic diversity of avian infectious bronchitis virus isolates in Korea between 2003 and 2006

Thirty-three field isolates of avian infectious bronchitis virus (IBV) were recovered from commercial chicken flocks in Korea between 2003 and 2006 and were characterized phylogenetically by nucleotide sequence analysis of the IBV S1 gene hyper-variable region. Our phylogenetic analysis revealed that recent field isolates of IBV formed at least three distinct phylogenetic types, including K-I, K-II, and K-III. K-I type IBV consisted of indigenous, 13 IBV isolates which evolved from the Kr-EJ/95 strain and then separated into the lineages of type K-Ia and type K-Ib. K-II type IBV isolates (n = 19) were closely related to nephropathogenic IBV variants from China and Japan. The K-III type isolate (Kr/D064/05), first identified by this study, was closely related to enteric IBV variants from the Chinese strains that cause proventriculitis. Sequence comparisons showed amino acid differences of >27.5% between IBV types. The molecular epidemiologic characteristics of IBV field isolates are briefly discussed.     

鸡传染性支气管炎病毒HN99株S1基因的克隆与序列测定

根据基因库中收录的鸡传染性支气管炎病毒 (IBV)S1基因的序列 ,设计了一对引物并采用RT -PCR扩增了鸡传染性支气管炎病毒HN99株的S1基因 ,扩增产物进行了克隆、测序 ,获得了IBVHN99株S1基因片段 ,其大小为1 739bp(含前导序列 ) ,其核苷酸序列与H1 2 0、H52、M41、Gray、Holte的S1基因核苷酸序列同源性较低 ,分别为 79.1 %,79.2 %,77.3%,77.8%,79 .4%,有大量的点突变并伴有基因插入和缺失 ;IBVHN99株的S1基因推导的氨基酸与H1 2 0、H52、M41、Gray、Holte株氨基酸的同源性分别为80 .1 %,79.9%,79.5%,78.5%,78.5%,经S1基因系统进化分析 ,提示IBVHN99株与其它各毒株的亲缘关系较远 ,初步证实IBVHN99株为一新的IBV毒株     

Vaccine efficacy against Ontario isolates of infectious bronchitis virus

Infectious bronchitis (IB) is an economically important viral disease with worldwide distribution. Every country with an intensive poultry industry has infectious bronchitis virus (IBV). The virus rapidly spreads from bird to bird through horizontal transmission by aerosol or ingestion. Sentinel bird studies were carried out in southern Ontario and IBV has been isolated from layer flocks. Genetic analysis of the S1 region of the strains showed that they were not vaccine related. The pathogenicity of selected Ontario variants of IBV isolates was studied and the subsequent work was to determine the degree of protection against field isolates provided by a commonly used vaccine MILDVAC-Ma5 in Ontario. The protection was evaluated by challenging immunized chickens with the respiratory (IBV-ON1) and nephropathogenic (IBV-ON4) viruses. The mean vaccine efficacy for IBV-ON1 was 66.7% indicating that a Massachusetts serotype vaccine would provide some protection against IBV field isolates.     

鸡传染性支气管炎病毒KIBVXJ株S1基因的克隆及序列分析

根据已发表的鸡传染性支气管炎病毒S1基因,设计并合成了一对引物,经RT-PCR扩增后获得全长约为1700bp的核苷酸序列。序列分析表明,S1基因的最大开放阅读框位于12位～1685位碱基之间,编码557个氨基酸;KIBVXJ株S1基因序列在19位～292位点的氨基酸区域内有较多的氨基酸置换、插入和与缺失现象;S1的裂解位点的序列为HRRRR,具有我国地方流行株的特征。KIBVXJ株的S1基因与国内外疫苗株的同源性分析表明,核苷酸同源率为73.8%～74.2%,氨基酸同源率为74.9%～76.0%。遗传进化分析表明,KIBVXJ株与国内外的主要疫苗株亲缘关系最远,与国内近年来分离的A2株、LX4株和QXIBV株的亲缘关系最近。     

鸡传染性支气管炎病毒分离鉴定及S1基因遗传演化分析

为调查辽宁地区鸡传染性支气管炎病毒(IBV)的流行及遗传演化情况,从辽宁某鸡场疑似鸡传染性支气管炎病料中分离得到1株病毒,经分子生物学检测、鸡胚矮小化试验、新城疫病毒血凝特性干扰试验和动物回归试验,确定该毒株为IBV,并命名为CH/LN/2019.扩增该毒株S1基因并进行序列分析发现,分离株S1基因全长1 620 nt...     

Evaluation of the protection conferred by commercial vaccines and attenuated heterologous isolates in China against the CK/CH/LDL/97I strain of infectious bronchitis coronavirus

Avian infectious bronchitis virus (IBV) causes tremendous economic losses to the poultry industry worldwide. Different serotypes of this virus show little cross-protection. The present study investigated the genotypic relationship between CK/CH/LDL/97I-type strains and reference IBVs based on S1 gene comparisons and the protection provided by vaccination with commercial vaccines and attenuated homologous and heterologous strains. Phylogenetic analysis and the comparison of S1 showed that CK/CH/LDL/97I-type virus might be a new serotype compared to vaccine strains and other types of IBV isolates in China. Protection efficacy was evaluated by morbidity, mortality, and virus re-isolation from the challenged chicks. Complete protection by IBV vaccination was provided by the homologous strain but sufficient respiratory protection was not provided by the commercial vaccines. Heterologous strains against CK/CH/LDL/97I challenge and the development of a vaccine against CK/CH/LDL/97I-type IBV will be necessary to control infectious bronchitis disease in poultry. Further development of the attenuated CK/CH/LDL/97I strain may provide a valuable contribution towards this goal.     

4株IBV中国地方分离株部分结构基因变异的研究

本研究通过RT-PCR分别获得了4个国内IBV分离株的S1、M和N基因，并进行了克隆及测序。序列分析结果表明：HaN2-95株的S1、M和N基因核苷酸序列均与IBV H120疫苗株的同源性最高；尽管HaN1-95株的S1基因与IBV H52疫苗株的亲缘关系最近，但是该毒株的M基因和N基因却与IBV Gray株的同源性最高；GX1-98株的S1和M基因均与IBV H52疫苗株的亲缘关系最近，但其N基因却与IBV Gray株和Ark99株有高度的同源性；GX2-98株的S1基因却与IBV Holte株的亲缘关系最近。上述结果提示国内有些IBV分离株的出现可能与疫苗株的使用有关。     

Isolation and identification of four infectious bronchitis virus strains in China and analyses of their S1 glycoprotein gene

Between 2003 and 2005, four strains of infectious bronchitis virus (IBV) were isolated from the vaccinated chicken flocks in China. The results from chicken embryo cross-neutralization assays showed that all the four isolates were relative to strain A2 of IBV, which was isolated in 1996 in Beijing and related to strain 4/91. The S1 gene of the spike protein was amplified and sequenced. The nucleotide and amino acid sequence of the S1 gene had a similar degree of identity (88.98-99.28%) among the four Chinese IBV isolates. The identity of the S1 protein gene between the four Chinese IBV isolates and 14 strains of other IBVs varied from 70.06 to 81.59%. Phylogenetic analysis suggested that there are at least four groups of IBVs circulating in China and the disease outbreaks might have been caused by infection of multiple strains of IBV.